There are inventions of water-driven wash brushes disclosed in U.S. Pat. No. 4,374,444 to Zhadanov; U.S. Pat. No. 4,679270 to Gaiti, et al; U.S. Pat. No. 4,809382 to Ravn; U.S. Pat. No. 5,007,127 to Paolo. All these water-driven wash brushes work with one or more brushes; which only rotate in the same direction at the same time on one single axle. But in daily life, when doing the normal cleaning job, the brush moves back and forth or up and down. This means the brush travels back and forth or up and down with two strokes, from point A to B and back from point B to A. While doing so, the forth stroke from point A to B, the bristles hit one side of the dirt that stick on the surface to be clean; and the backward stroke, the bristles hit the other side of the dirt. As a result of moving back and forth or up and down, it will remove the dirt much faster than just move the brush only in one direction from point A to B. According to the general principle of cleaning action mentioned above, this invention works with two concentric brushes rotating in opposite direction simultaneously; the brush A will do the forth stroke and the brush B will do the backward stroke at the same time. With this present invention, when the two concentric brushes unit travels from point A to B, the two back and forth strokes have already been carried out at the same time in one stroke by the two concentric brushes. So the job is done and there is no need to travel back from point B to A. With this invention, it can save half of the time in cleaning as well as half of water used while doing the same cleaning job; should be considered as an environmental friendly device.